// Copyright (c) 2020, the Dart project authors. Please see the AUTHORS file
// for details. All rights reserved. Use of this source code is governed by a
// BSD-style license that can be found in the LICENSE file.

main() {
  dynamic c;
  c?.[42];
  c?.[42] = 42;
  c?.[42]++;
  ++c?.[42];
  c?.[42]?.[0];
  c?.[42]?.[0] ??= 42;
  c?.[42]?.[0]++;
  ++c?.[42]?.[0];
}